Method and apparatus for treating oils



Sept. 5, 1933. w. G. LAIRD METHOD AND APPARATUS FOR TREATING OILS Filed July 50, 1926 DSQQQ Qui-HL Patented Sept. 5, i335 Wilbur CG. Laird, New York, N. Y., assigner to Heat Treating Company, New York, N. Y., a corporation or Delaware Application .luly Sli, i926. Serial No., 125,893

6 Claims.

rThis invention relates to the art of treating crude oil or crude dis'tillates to produce valuable commercial products therefrom.

More particularly the invention relates to the cracking of petroleum oils under pressure and the treatment of the residuum from the reaction chamber to recover a distillate suitable to be again cracked.

In accordance with known methods the hot 10 residuum formed in a pressure still is withdrawn -from the reaction chamber into a separate vessel where the lighter volatiles are distilled on by the potential heat in the highly heated liquid. This is done by releasing the pressure and permitting the materials which will volatilise at the reduced pressure to distill olf. The handling of this highly heated oil through pipes and valves and releasing the pressure thereon at so high a temperature is not without considerable danger, especiald ly in view of the fact that the oil is at a temperature considerably above its flash point. Furthermore, such methods are wasteful in that the work required to put the oil under pressure is lost when the pressure is released.

Accordingly, one object of the invention is to provide a method of recovering a recycle cracking stock from pressure still residuuin by holding the residuum under substantially the saine pressure as the pressure existing in the cracking still.

In accordance with this object one feature of the invention contemplates stripping the recycle stock from the residuurn by a gas circuit wherein the residuuni is cooled and in good condition to have its pressure reduced in order to remove the stripped residuum from the still or cracking equipment.

Another object of the present invention is to provide a method and apparatus by which the residuurn withdrawn from the reaction chamber may be treated safely and eiiiciently for the removal of the more desirable fractions.

Another object is to provide a method 'of distilling the residuurn under pressure whereby the condensate recovered may be reintroduced into the cracking system with a minimum. power consumption.

A further object of the present invention is to prevent the return to the healing zone of the light volatiles such as gasoline, which is absorbed or occluded in the residuum withdrawn from the reaction chamber.

The novel features of the invention are pointed out in the appended However, the invention itself, with other objects and advantages will behest understood from the following de- Cil scription taken in conjunction with the4 accompanying drawing, in which The ligure is a diagrammatic view in elevation of an apparatus accordingl to the invention, and adapted to operate in accordance with the novel 60 method.

In accordance with the invention the oil to be cracked or distilled, and which may be either a crude oil or distillate thereof, is introduced into the system. from any suitable source of supply through conduit 2, pump d and conduit 6. As seen the oil rst enters the system through dephlegrnating tower 8, where it passes downward in heat interchange relation to but out of contact with vapors passing upward and reflux condensate passing downward, iinally leaving the tower near its lower end by conduit lo. The preheated oil passes through the conduit lo to coil still l2, in heater le, in which the oil is heated to the desired distilling or cracking temperature, then through conduit i6, controlled by valve 18, into an enlarged reaction scrubber 20, in which the vapors produced are permitted to separate from the unvaporized oil and residuum. The vapors leave the reaction scrubber 2S and enter the lower part of the dephlegniator 8 by conduit 22, and as previously mentioned pass upward in neat interchange with charging oil. Vapore 'remaining uncondensed in tower pass over through conduit 2li controlled by valve 26 into condenser 28 and receiver 3o, from rwhich the condensate, gasoline, is removed by pipe line 32, controlled by valve Srl, and the non-condensable gases by pipe line 36, Some of the withdrawn by pipe 36 are returned to the system by compressor 38 and valve controlled pipe fr0, as will be explained later, while the excess gas is withdrawn by valved pipe e2.

The tower or column 8 referred to above and 95 shown diagiarnmatically in the drawing is shown and described in detail in my copending application Serial No. 325,892, l July 3G, 1926.

The reaction scrubber 21u comprises an inclined cylindrical chamber in which depending transverse baffle plates Llll cause the vapors entering at the lower end from conduit 16 to bubble through liquid, ina----tained on the upper sides of these bafes, before leaving the chamber by conduit 22, it is clear that the levels of the liquid in chamber 2t will be substantially that shown by the dotted lines between the baffles because o the necessity t1 at the gases pass under the bailies .Due to the inclination of the reaction char-ober the heavier products, such as the sludge, carbon and residue produced in cracking and distilling oils, gravitate to the lower end of the chamber and are removed by draw-on conduit 46 controlled by valve 48. Oil which is freed of the settled residuum may be withdrawn from the upper end of the chamber 20 by pump 50 in conduit 52 and returned to the heater through conduit 10, as shown, or the whole liquid residue may be discharged with the residuum through conduit 46.

The residuum withdrawn through pipe 46 passes into a topping still 54, maintained under substantially the same or higher pressure than reaction scrubber 20. This topper as shown comprises aseries of alternating baies 56 and 58 over which the residuum iiows and around which gases introduced through serrated distributor 60, in the lower part of chamber 54, must pass. Gas is supplied to the distributor 60 by compressor 38, and valved pipe 40, previously referred to. The vapors removed are introduced directly into the lower end of reaction scrubber 20 by pipe 62, where they mingle with oil andvapors introduced from the heater by conduit 16.

The topped residuum produced in chamber 54, is advanced to a second chamber 64, through a conduit 66 controlled by a valve 68, where the residuum is stripped of oil suitable for recycling through the cracking system.Y This chamber is provided with baille plates 56 and 58 and a distributor '70, being similar in construction and operation to chamber 54.

While the residuum entering this chamber is at a high temperature the chamber may be heated by any suitable means for example by burner 72. The vapors escaping through valve controlled vapor line '74 pass into condenser coil '76 and trap 78, from which distillate is withdrawn by pipe 80, and gas by pipe 82 and booster 84. The distributor 70 is supplied with gas by booster 84 through pipe 86, excess or makeup gas being removed from or supplied to the system by valved branch pipe 88. Residuum from the stripping still 64 passes by conduit 90 to cooling coil 92, then to any desired point by valved pipe 94, to be used as fuel. By opening the valve in pipe 94 the pressure in the system will force the fuel oil from chamber 64, through conduit 90 and coil 92.

In order to prevent heat loss in the system the various chambers and conduits are preferably lagged with suitable heat-insulating material.

The reflux condensate which accumulates in the bottom of the tower 8, is withdrawn, by valved pipe 96, preferably after being stripped of gasoline vapors and may be introduced into the feed stream at 2 or any other point along the tower.

The recycle distillate from the stripper is preferably reintroduced through pump 4 into the system, but may be added to the charging stock at any point along the tower, where its cooling effect on the vapors would be more advantageous.

As will be recognized by those skilled in the art, the residuum withdrawn from the reaction scrubber contains a small percentage of occluded and absorbed gasoline, a considerable quantity of material suitable for recycling through the system,V and a nal residue constituting a valuable fuel oil. The gasoline in the residuum is removed in topper 54 by introducing into the mass of the residuum a small amount of gas which acts to reduce the partial pressure of gasoline vapors in the chamber and a dilutent to drive out the gasoline vapors. The residuum withdrawn from the chamber 20 into the topper 54 is removed from the iniluence of the cracking conditions maintained in chamber 20 so that no substantial amount of cracking occurs except that which would naturally occur in a hot withdrawn residuum.

The topped residuum is treated in chamber 64 to strip it of oil that would be suitable for retreatment in the cracking or distilling system. This operation is carried out under a pressure substantially equal to or greater than that maintained in chamber 20 and 54. The stripping may be accomplished almost entirely by the gas passed through the distributor '70 which by its presence reduces the partial pressure of oil vapors over the hot residuum and at the same time acts as a carrier in removing the vapors to the condenser. The closed circuit comprising the stripper, condenser and booster constitutes a very simple and efcient means of removing the desired distillate from the residuum, since the same gas can be used over and over again. However, if necessary to speed up the operation or to add heat continuously with certain types of oil, the burner '72 may be used or chamber 64 may be surrounded by a masonry heating chamber.

The residuum may pass in a continuous stream from the reaction scrubber through chambers 54 and 64 or may be withdrawn at intervals as desired. In practice chambers 54 and 64 may be at successively lower levels than chamber 20, so that the residuum will drain from one to the other or pumps may be used in lines 46 and 66.

From the foregoing description it will be apparent that the system increases the economy and e'iciency in cracking and distilling operations. As examples it is pointed out that by maintaining the pressure substantially equal in the whole apparatus the power used to recycle the distillate from trap '78 is reduced as well as allowing the return of the gasoline vapors from the topping chamber to the reaction chamber. Furthermore the return of the gasoline vapors from the residuum direct to the reaction chamber increases the yield by concentrating the gasoline toward the final condenser and at the same time preventing its return with the recycle distillate to the heating coil. Thus any gasoline produced in the cracking or distilling operation is constantly advanced to the final condenser and not lost in the residuum or cracked to gas by being passed through the cracking coil.

What I claim is:

1. In the method of cracking oils in which oil is heated to a cracking temperature under a superatmospheric pressure and passed to an enlarged zone to permit the separation of vapors from residual oil, the improvement which comprises, removing the residual oil from said zone, topping said residual oil without further cracking the same to remove light gasoline vapors therefrom Vand introducing vsaid light vapors into said enlarged zone.

2. In the method of cracking oils in which oil is heated to a cracking temperature under a superatmospheric pressure and passed to an enlarged zone to permit the separation of vapors from residuum, the improvement which comprises, removing the residuum from said Zone, and without further cracking the same bubbling gas through said residuum to remove light gaso- 1 Cil ping the resulting residuum to obtain a crack ing stock, condensing the stripped vapors and separating non-condensible gases therefrom and returning said gases through said resulting residuurn in a closed cycle separate from the cracking system.

4. in an apparatus for treating liquids the combination of a liquid heater, an enlarged chamber receiving liquid and vapors from said heater, a topping still receiving liquid residuum from said chamber, a stripping still receiving topped residuum from said topping still, means for conducting vapors from said topping still to said chamber, means for condensing the vapors rcrn said stripping still and means for bubbling gas through residuum in said stills.

5. The method of cracking oil, comprising passing oil through a heating zone and into an enlarged Zone where vapors are allowed to separate from residual oil, withdrawing said residual oil from the enlarged Zone, topping said residual oil to remove absorbed and occluded low boiling point constituents therefrom in a zone in which the withdrawn oil is not subjected to further cracking conditions but under substantially the pressure maintained in the said enlarged zone, introducing said removed low boiling point constituents into said enlarged Zone, stripping the topped residue of relatively high boiling point constituents, and condensing the resulting high boiling point vapors.

6. The method of cracking oils as dened in claim 5 in which said stripping operation comprises distilling said topped residue by circulating a gas under pressure through a closed cycle including a condenser, a booster and a chamber, in which said topped residue is contained.

WILBUR Gr. LAIRD. 

